Old sheep raising the baaa

Sep 05, 2008
Oldest sheep make larger contributions to population growth when conditions are harsh. Credit: Owen Jones

Populations of wild animals face the challenge of surviving in a changing climate. Researchers at Imperial College London and Université Claude Bernard Lyon have shown how a sheep population on a remote island off the west coast of Scotland responds to two consequences of climate change: altered food availability and the unpredictability of winter storms.

Dr. Thomas Ezard, lead author of the study, revealed, "When times are good and food is plentiful, lambs contribute almost twice as much to changes in population size than when times are hard. On the flip side, the oldest sheep contribute most to population growth when conditions are harsh." The work, published in the September issue of The American Naturalist, suggests that the dynamics of populations are influenced not only by the weather but also by the ability of individuals to respond to it.

New mathematical breakthroughs have made it possible to show how environmental change affects populations, like these sheep. The key is appreciating (1) how weather affects individual sheep and (2) how the weather changes from one year to the next. If consecutive years have similar weather, the dynamics of the population will be very different than if conditions are unrelated from one year to the next.

Professor Tim Coulson concluded, "A thorough understanding of the likely effects of climate change on the ecology of wild populations requires linking populations to their environment. This demands application of innovative mathematical methods, as used here."

Citation: Thomas H. G. Ezard, Jean-Michel Gaillard, Michael J. Crawley, and Tim Coulson, "Habitat Dependence and Correlations between Elasticities of Long-Term Growth Rates." American Naturalist (2008) 172:424-430.

Source: University of Chicago

Explore further: New class of insecticides offers safer, more targeted mosquito control

Related Stories

Ag-tech could change how the world eats

Dec 14, 2014

Investors and entrepreneurs behind some of the world's newest industries have started to put their money and tech talents into farming - the world's oldest industry - with an audacious agenda: to make sure there is enough ...

Study solves the bluetongue disease 'overwintering' mystery

Sep 12, 2014

The bluetongue virus, which causes a serious disease that costs the cattle and sheep industries in the United States an estimated $125 million annually, manages to survive the winter by reproducing in the insect that transmits ...

Wild sheep show benefits of putting up with parasites

Aug 07, 2014

In the first evidence that natural selection favors an individual's infection tolerance, researchers from Princeton University and the University of Edinburgh have found that an animal's ability to endure ...

Recommended for you

Scientists discover new 'transformer frog' in Ecuador

16 hours ago

It doesn't turn into Prince Charming, but a new species of frog discovered in Ecuador has earned the nickname "transformer frog" for its ability to change its skin from spiny to smooth in five minutes.

Longer DNA fragments reveal rare species diversity

16 hours ago

A challenge in metagenomics is that the more commonly used sequencing machines generate data in short lengths, while short-read assemblers may not be able to distinguish among multiple occurrences of the ...

Scientists say polar bears won't thrive on land food

16 hours ago

A group of researchers say polar bears forced off melting sea ice will not find enough food to replace their current diet of fat-laden marine mammals such as seals, a conclusion that contradicts studies indicating ...

The vital question: Why is life the way it is?

18 hours ago

The Vital Question: Why is life the way it is? is a new book by Nick Lane that is due out on April 23rd. His question is not one for a static answer but rather one for a series of ever sharper explanations—explanations that a ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.